Image pickup apparatus, and image correction method

ABSTRACT

To provide an image pickup apparatus which enables acquisition, by a simple configuration, of a natural image of a dark place or the like at the time of image pickup in a dark environment by eliminating an influence from the surrounding environmental light, an image pickup apparatus of the invention includes an image pickup section for picking up an image of an object and acquiring an image signal, an accumulation section for sequentially accumulating outputs from the image pickup section, a display section for visibly displaying an accumulated image signal of the accumulation section, a position identification section for identifying a position specified on an image displayed on the display section; and a correction section for performing an image correction process on the accumulated image signal of the accumulation section according to an identification result of the position identification section.

This application claims the benefit of Japanese Application No.2013-100344 filed in Japan on May 10, 2013, the contents of which areincorporated herein by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an image pickup apparatus and an imagecorrection method allowing appropriate black balance correction in imagepickup in a dark environment.

2. Description of the Related Art

Conventionally, an image pickup apparatus that is capable ofsequentially converting optical images formed by an image pickup opticalsystem into image signals by a photoelectric conversion device or thelike and of storing the image signals thus obtained in a storage mediumas pieces of image data of a predetermined format, and configured byincluding an image display device, for example, a liquid crystal display(LCD), that reproduces/displays the image data stored in the storagemedium as an image, such as a digital camera or a camcorder (hereinafterreferred to collectively as camera(s)), has been put to practical useand widely used.

When using this type of camera and performing image pickup of a nightscene by a long exposure, for example, if the exposure time is long,artificial light from street lamps, neon lights or the like may affectthe entire screen. For example, a region in the screen which is supposedto be dark, such as a region of night sky, may not be black, and may beshown to be brighter than it looked due to the influence of artificiallight or the like, or faint light images of stars or the like may beerased. Also, the original color of a target object in a dark place maynot be reproduced due not only to the artificial light, but also tounintentional diffraction of environmental light.

Accordingly, various proposals are conventionally made in, for example,Japanese Patent Application Laid-Open Publication No. 2005-45558, withrespect to an image correction processing technique for acquiring animage that is closer to the way of being seen by human beings by takinginto account the influence of harmful light such as artificial light.

An image pickup apparatus disclosed in Japanese Patent ApplicationLaid-Open Publication No. 2005-45558 mentioned above performs blackbalance control of correction in a neutral axis direction, also in thecase the darkest point in the image is shifted from a neutral axis, bytaking into account the adaptation effect of human eyes to black (therate of dark adaptation).

SUMMARY OF THE INVENTION

An image pickup apparatus of an aspect of the present invention includesan image pickup section for picking up an image of an object andacquiring an image signal, an accumulation section for sequentiallyaccumulating outputs from the image pickup section, a display sectionfor visibly displaying an accumulated image signal of the accumulationsection, a position identification section for identifying a positionspecified on an image displayed on the display section; and a correctionsection for performing an image correction process on the accumulatedimage signal of the accumulation section according to an identificationresult of the position identification section

An image correction method of an aspect of the present inventionincludes steps of picking up an image of an object and acquiring animage signal by an image pickup section, sequentially accumulatingoutputs from the image pickup section by an accumulation section,visibly displaying an accumulated image signal of the accumulationsection using a display section, identifying a position specified on animage displayed on the display section by a position identificationsection; and performing a correction process, by a correction section,on the accumulated image signal of the accumulation section according toan identification result of the position identification section.

The advantages of this invention will be further clarified by thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block configuration diagram schematically showing a maininternal configuration of an image pickup apparatus (camera) of anembodiment of the present invention;

FIG. 2 is a conceptual diagram for describing image pickup of a desiredobject by an operator (user) using the image pickup apparatus (camera)in FIG. 1, the diagram showing a sketch of an image pickup rangeincluding a sight which is an image pick target;

FIG. 3 is a conceptual diagram showing picking up of the image pickuptarget in FIG. 2 using the image pickup apparatus (camera) in FIG. 1;

FIG. 4 is a conceptual diagram showing display of an image pickup result(image) picked up using the image pickup apparatus (camera) in FIG. 1 ona display section;

FIG. 5 is a conceptual diagram showing a change over time in the amountsof accumulated charges of RGB signals of a picked-up image picked up byusing the image pickup apparatus (camera) in FIG. 1;

FIG. 6 is a flowchart showing an example of a process sequence of theimage pickup apparatus (camera) in FIG. 1 (long-exposure image pickup);

FIG. 7 is a conceptual diagram for describing image pickup of a desiredobject by an operator (user) under another image pickup state using theimage pickup apparatus (camera) in FIG. 1, the diagram showing a sketchof an image pickup range including a sight and a main object (person) asimage pickup targets (predicted acquired image);

FIG. 8 is a conceptual diagram showing picking up of the image pickuptargets in FIG. 7 using the image pickup apparatus (camera) in FIG. 1;

FIG. 9 is a conceptual diagram showing display, on a display section, ofan image pick result (image) picked up using the image pickup apparatus(camera) in FIG. 1;

FIG. 10 is a flowchart showing another example of the process sequenceof the image pickup apparatus (camera) in FIG. 1 (slow synchronizationimage pickup);

FIG. 11A is a diagram for describing another embodiment of the presentinvention, and is a conceptual diagram showing a change over time in theamounts of accumulated charges of RGB signals of a picked-up imagepicked up by using the image pickup apparatus (camera) in FIG. 1;

FIG. 11B is a conceptual diagram of the amounts of accumulated chargesafter performance of color space conversion from the state in FIG. 11A;

FIG. 12 is a graph showing, for the other embodiment shown in FIGS. 11Aand 11B, an example of a relation of a correction factor α to thebrightness at a touch position;

FIG. 13 is a graph showing, for the other embodiment shown in FIGS. 11Aand 11B, an example of a relationship between an amount of accumulatedcharges and an output (gamma table);

FIG. 14 is a diagram for describing another embodiment of the presentinvention, and is a diagram showing a sketch of an image pickup range,including a sight as an image pickup target, of image pickup by theimage pickup apparatus (camera);

FIG. 15 is a conceptual diagram showing an example of a gradationalchange along a straight line ab (vertical line V including a touch pointT) in FIG. 14; and

FIG. 16 is a graph showing, for the embodiment of FIG. 14, an example ofa relationship between a ratio (C/T) between the brightness at the touchpoint T and the brightness at a point C and the amount of correction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described with reference toembodiments shown in the drawings. In each of the drawings used in thefollowing description, the scale of display of each structural componentmay be different such that each structural component is large enough tobe recognized in the drawing. Accordingly, the present invention is notrestricted to the modes shown in the drawings with respect to the numberof structural components, the shapes of the structural components, theproportion of the sizes of the structural components, and the relativepositional relationship of respective structural components.

Each embodiment of the present invention described below illustrates, asan image pickup apparatus to which the present invention is applied, animage pickup apparatus (hereinafter referred to simply as “camera”)configured to be capable of photoelectrically converting, by using asolid-state image pickup device, an optical image formed by an opticallens or the like, of storing an image signal thus obtained in a storagemedium as digital data representing a still image or a movie, and also,of reproducing/displaying the still image or the movie on a displaydevice based on the digital image data stored in the storage medium.

First, a schematic configuration of a camera which is an image pickupapparatus according to an embodiment of the present invention will bedescribed, FIG. 1 is a block configuration diagram showing a maininternal configuration of an image pickup apparatus (camera) of anembodiment of the present invention.

As shown in FIG. 1, a camera 1, which is the image pickup apparatus ofthe present embodiment, is configured from a camera body 10, and a lensbarrel 20. The camera 1 is a so-called interchangeable lens cameraconfigured in such a way that the lens barrel 20 may be freelyattached/detached with respect to the camera body 10. Note that thepresent embodiment gives a description citing the interchangeable lenscamera as an example, but a camera to which the present invention may beapplied is not limited to such mode, and application to a camera whichis configured by integrating the camera body 10 and the lens barrel 20,for example, is possible in exactly the same manner.

The camera body 10 is configured by including a signal processingcontrol section 11, a body-side communication section 12, an imagepickup device 13, a storage section 14, an operation section 15, atemporary storage section 16, an acceleration/angular velocity sensor17, a display section 18, a touch panel 18 b, a clock section 19, arotation determination section 30, a face detection section 31, anaccessory communication section 32, and the like.

The signal processing control section 11 has a function as a controlsection for controlling the operation of the camera 1 in an overallmanner, and is a circuit section having a function of a signalprocessing section for processing control signals for controllingvarious structural units and for performing image signal processing andthe like on an image signal (image data) acquired by the image pickupdevice 13.

Various circuit sections are provided inside the signal processingcontrol section 11, such as an accumulation section 11 a, an imageprocessing section 11 b, a touch determination section 11 c, a displaycontrol section 11 d, and the like.

Of the above, the accumulation section 11 a is an image signalprocessing circuit section for performing image processing of receivingand accumulating image signals outputted from the image pickup device13.

The image processing section 11 b is a signal processing circuit sectionfor performing various types of image processing based on image dataacquired by the image pickup device 13.

The touch determination section 11 c is a signal processing circuit forreceiving an instruction input signal from the touch panel 18 b, and fordetermining the instruction content. For example, determinationprocesses of determining, when a touch operation on the touch panel 18 bis performed, the touch position and the coordinates on the displayimage on the display section 18, and of identifying, when instructionicon display or the like is performed on the display image on thedisplay section 18, the position (coordinates) corresponding to the icondisplay or the like are performed. In this manner, the touchdetermination section 11 c functions as a position identificationsection. Various types of control at the signal processing controlsection 11 are performed based on the determination result of the touchdetermination section 11 c.

The display control section 11 d is a control circuit section fordriving and controlling the display section 18. The display controlsection 11 d performs control of receiving image data generated andacquired by an image pickup section including the image pickup device13, a lens 26, and the like (described below), and of displaying theimage data on a display panel of the display section 18 as an image.

The image pickup section mentioned above is a unit configured byincluding the lens 26 and the like (described below), which is an imagepickup optical system that passes light from a target object (object)which is an image pickup target and forms an optical image of theobject, and the image pickup device 13 that receives the object imageformed by the lens 26 and performs a photoelectric conversion process.

As the image pickup device 13, for example, a photoelectric conversiondevice, which is a solid-state image pickup device such as an MOS imagesensor using a MOS (metal oxide semiconductor) or the like or a CCDimage sensor using a circuit element such as a CCD (charge coupleddevice) or the like, is used. An analog image signal generated by theimage pickup device 13 is outputted to, and accumulated by, theaccumulation section 11 a of the signal processing control section 11,and is then outputted to the image processing section 11 b to havevarious types of image signal processing performed thereon.

The storage section 14 is a structural section configured by including asignal processing circuit section for converting an image signaloutputted from the image pickup device 13 and processed by the imageprocessing section 11 b into a predetermined format, a storage mediumfor storing image data generated by the signal processing circuitsection, a control section for driving and controlling the storagemedium, and the like. The conversion process of an image signal that isperformed at this time is a process of conversion into image data of astoring format by a signal compression process or the like, signalprocessing of restoring an image signal by reading image data stored inthe storage medium and performing an extension process thereon, or thelike, for example. Note that this type of compression/extension processis not limited to be performed by the signal processing circuit sectionincluded in the storage section 14, and may be performed by a similarsignal processing circuit section by providing such a section in thesignal processing control section 11, for example.

The temporary storage section 16 is a circuit section for temporarilystoring image data acquired by the image pickup device 13 and the like,and a semiconductor memory device such as an EEPROM (electricallyerasable programmable read only memory), a RAM (random access memory) orthe like is used, for example.

The operation section 15 includes various types of operation members,such as an operation member of a normal push button type, a slide type,a dial type or the like, provided to the package portion of the camerabody 10 of the camera 1, and refers to structural sections for operationincluding various general operation members such as a shutter releasebutton (not particularly shown). Note that, as the operation memberincluded in the operation section 15, there is also a so-called four-wayoperation member, for example. This four-way operation member is usedalso in the case of selecting an item on a menu screen displayed on thedisplay section 18, or of issuing an instruction regarding a position ona display image, for example. The four-way operation member functions asan alternative operation member to the touch panel 18 b described below.An instruction signal from the four-way operation member is outputted tothe signal processing control section 11, and position identification orthe like is performed by a control circuit in the signal processingcontrol section 11. Accordingly, in this case, the signal processingcontrol section 11 functions as a position identification section fordetermining a position on an image displayed on the display section 18,for example.

Also, the camera 1 of the present embodiment includes the touch panel 18b as an operation member for operation different from the operationsection 15. This touch panel 18 b is an operation member arranged on thedisplay surface of the display section 18, and is configured in such away that various operation instruction signals are generated when anoperator (user) performs a touch operation, a slide operation and thelike on a predetermined region corresponding to an image being displayedon the display panel. An instruction input signal from the touch panel18 b is sent to the touch determination section 11 c of the signalprocessing control section 11, and the operation input is determined.

The display section 18 is a structural section for performing imagedisplay under the control of the display control section 11 d based onimage data or the like outputted from the image pickup device 13 orimage data or the like on which the extension process has been performedby the storage section 14. As the display section 18, a display panelsuch as a liquid crystal display (LCD), a plasma display (PDP), or anorganic electro-luminescence display (OEL) is used, for example. Thisdisplay section 18 has a function of reproducing/displaying an imagebased on image data which has been picked up and stored, and alsofunctions as a viewfinder used for observing and checking an imagepickup range at the time of an image pickup operation by sequentiallyand continuously receiving image data outputted from the image pickupdevice 13 through the image processing section 11 b and keep displayingthe image. Note that as the display section 18, a small panel to be usedas an electric viewfinder (EVF) may also be provided in addition to adisplay panel provided to the rear surface of the apparatus.

Note that, in the case of a normal camera, the range that can beobserved by using the viewfinder is referred to as the field of view ofthe viewfinder, but as described above, the camera 1 of the presentembodiment uses, as the viewfinder, a display device that displays animage based on image data outputted from the image pickup device 13.Thus, the observation image that may be observed by the display section18, which is the viewfinder, of the camera 1 of the present embodimentis a display image based on the image data. Accordingly, in thefollowing description, the image displayed on the display section 18 asthe viewfinder will be referred to as a viewfinder image.

The clock section 19 is an internal clock of a computer called areal-time clock (RTC). The clock section 19 is used at the time ofattaching date information of a data file, or of time keeping or timecontrol during a control process, for example.

The acceleration/angular velocity sensor 17 is a detection signalprocessing circuit section including an angular velocity sensor or thelike for detecting the attitude of the camera 1 with respect to thehorizontal or vertical direction, that is, the state of inclination (forexample, the angle of elevation) with respect to the vertical directionof the optical axis of the image pickup optical system, for determiningthe attitude state with respect to the way the camera 1 is held, thatis, the way of holding at the vertical position or the horizontalposition, or in other words, the up-down direction of an image(accelerometer), and for measuring the amount of rotation of the camera1 around an axis orthogonal to the optical axis. As theacceleration/angular velocity sensor 17, a gyroscope as an angularvelocity sensor is used, for example.

The rotation determination section 30 is a determination circuit sectionfor determining whether or not the camera 1 is rotated around theoptical axis, and determining the rotation direction and the like in thecase the camera 1 is rotated, based on information about a change in theattitude of the camera 1 detected by the acceleration/angular velocitysensor 17 or the like. A display image rotation process for displayingan image being displayed on the display panel of the display section 18appropriately with respect to the top-bottom, left-right relationship isperformed by the image processing section 11 b upon reception of adetermination result of the rotation determination section 30.

The face detection section 31 is an image signal processing circuitsection as an object detection section for detecting whether an imagecorresponding to an object such as the face of a person, or a specificanimal or plant (for example, a dog, a cat, a bird, or a flower) ispresent in an image that is displayed based on the image data which hasbeen acquired by the image pickup device 13 and which has been outputtedafter image processing by the image processing section 11 b. The facedetection section 31 may perform color detection or pattern detection,for example, in addition to detecting a face image. Then, with respectto the object detected by the face detection section 31, the signalprocessing control section 11 performs control of maintaining focus on afollowed object at all times by automatically following a moving body inthe images.

The accessory communication section 32 is a circuit section forperforming communication with an accessory 40 attached to the camerabody 10. The signal processing control section 11 performs control ofthe accessory 40 through the accessory communication section 32. Theaccessory 40 here may be various devices to be used in conjunction withthe camera 1 by being selectively attached to an accessory attachingsection (a part called an accessory shoe, a hot shoe, or the like; notshown) provided on the outer surface (for example, the upper surface orthe like) of the camera body 10.

To this end, a connection terminal (not shown) for being electricallyconnected to the accessory communication section 32 is provided to theaccessory attaching section. A connection terminal to be electricallyconnected to an internal electrical circuit is correspondingly providedto the accessory 40. According to this configuration, when the accessory40 is attached to the accessory attaching section, the attachedaccessory 40 is electrically connected to the accessory communicationsection 32 of the camera 1. Then, the signal processing control section11 on the side of the camera body 10 reads unique information and thelike from an information storage section 40 a of the attached accessory40 through the accessory communication section 32, and performs acorresponding drive control process as appropriate.

Note that, as concrete examples of the accessory 40, there are a flashdevice, a light source device, an electric viewfinder (EVF), amicrophone connection apparatus, an external communication apparatus,and the like. As shown in FIG. 1, the accessory 40 includes, insideitself, the information storage section 40 a storing the uniqueinformation and the like of the accessory 40. Also, although not shownin FIG. 1, unique structural units, control circuits and the likecorresponding to respective apparatuses are provided inside theaccessory 40. Note that each apparatus as the accessory 40 is notdirectly relevant to the present invention, and detailed descriptionthereof is omitted.

The body-side communication section 12 is a signal processing circuitsection for communication on the side of the camera body 10 forexchanging control signals, information signals, and the like betweenthe camera body 10 and the lens barrel 20, by being electricallyconnected to a lens-side communication section 22 described below.

Now, the lens barrel 20 is configured mainly from a lens control section21, the lens-side communication section 22, a lens-side operationsection 23, a zoom drive section 24 a, a focus drive section 24 b, azoom lens position detection section 25 a, a focus lens positiondetection section 25 b, a lens 26, which is an image pickup opticalsystem, a lens-side storage section 27, and the like.

The lens control section 21 is a control section for controlling theoperation of each structural unit on the side of the lens barrel 20under the control of the signal processing control section 11 on theside of the camera body 10.

The operation section 23 collectively refers to a plurality of operationmembers and the like such as a focus ring for performing a switchingoperation at the lens side, such as switching between a normal imagepickup mode and a close-up image pickup mode, operations such as anautofocus (AF) operation and a manual focus (MF) operation, and a focusadjustment operation, a zoom ring for performing a zoom operation, anelectric zoom switch, and the like.

The zoom drive section 24 a is a drive unit including a drive motor fordriving a zoom optical system, of the lens 26, related to a zoomoperation, a drive mechanism for transmitting the drive force, and thelike. Also, the focus drive section 24 b is a drive unit including adrive motor for driving a focusing optical system, of the lens 26,related to a focus operation, a drive mechanism for transmitting thedrive force, and the like.

The zoom lens position detection section 25 a is a position detectioncircuit for detecting the position of the zoom optical system on theoptical axis. Moreover, the focus lens position detection section 25 bis a position detection circuit for detecting the position of thefocusing optical system on the optical axis.

The lens-side storage section 27 is a circuit section for storageincluding a storage medium in which various pieces of informationregarding the lens barrel 20, and the like are stored in advance. Thevarious pieces of information stored in the storage section 27 are usedas appropriate and as necessary by being transferred to the side of thecamera body 10 from the lens control section 21 through each of thecommunication sections 22 and 12. As this lens-side storage section 27,a non-volatile semiconductor memory device such as an EEPROM, a ROM(read only memory), a flash memory or the like is used.

The lens 26 includes, in addition to an image pickup optical system,configured from a plurality of optical lenses or the like, for formingan optical image of an object, a plurality of lens barrel members forholding respective optical lenses of the image pickup optical system,lens barrels for driving for separately moving each of the plurality oflens barrel members back and forth in the optical axis direction, andthe like, a zoom control section 26 a for controlling the zoom opticalsystem which is a part of the image pickup optical system, a focuscontrol section 26 b for controlling the focusing optical system whichis a part of the image pickup optical system, a diaphragm mechanism foradjusting the amount of a luminous flux passing through the image pickupoptical system, a diaphragm control section 26 c for driving andcontrolling the diaphragm mechanism, and the like. As described above,the image pickup section is configured from the lens 26 and the imagepickup device 13 of the camera body 10. Note that the concreteconfiguration of the lens barrel 20 is assumed to be substantially thesame as the configuration of a general zoom lens barrel used for aconventional camera, and detailed description and illustration thereofwill be omitted. Here, as an example of the lens barrel 20, a lensbarrel including a zoom lens optical system is cited, but this mode isnot restrictive, and a lens barrel including a normal fixed focal lengthlens optical system may also be used.

The lens-side communication section 22 is a signal processing circuitsection for communication on the side of the lens barrel 20 forexchanging control signals, information signals and the like between thelens barrel 20 and the camera body 10, by being electrically connectedto the body-side communication section 12.

Note that the camera body 10 and the lens barrel 20 are configured byincluding other various structural units and the like in addition to thestructural sections described above, but these various structural unitsand the like are structures not directly relevant to the presentinvention, and detailed description and illustration of the units areomitted assuming that the units have the same structures as those of ageneral, conventional camera.

For example, a shutter mechanism for opening/closing the optical path ofthe image pickup optical system, and adjusting the amount of luminousflux passing through the image pickup optical system at the time of animage pickup operation is not illustrated nor described, but the camera1 of the present embodiment also includes a normal shutter mechanism thesame as that of a conventional camera. This shutter mechanism may be afocal plane shutter arranged on the side of the camera body 10, or alens shutter arranged on the side of the lens barrel 20. In the case theshutter mechanism is arranged on the side of the camera body 10, theshutter mechanism is controlled mainly by the control section on thebody side. Also, in the case the shutter mechanism is arranged on theside of the lens barrel 20, the shutter mechanism is controlled mainlythrough the lens control section 21 under the control of the controlsection on the body side.

The outline of the action at the time of performing image pickup usingthe camera 1 of the present embodiment configured in the above mannerwill be described below. FIGS. 2 to 4 are conceptual diagrams showingimage pickup of a desired object by an operator (user) using the camera1 of the present embodiment. Of these drawings, FIG. 2 is a diagramshowing a sketch of an image pickup range including a sight which is animage pickup target. FIG. 3 is a conceptual diagram showing picking upof the image pickup target in FIG. 2 using the camera 1 of the presentembodiment. FIG. 4 is a conceptual diagram showing display of an imagepick result (image) picked up using the camera 1 of the presentembodiment on a display section.

In the case of taking, as the target of image pickup, an image pickuptarget 200 as shown in FIG. 2, for example, a scene where thesurrounding environment is relatively dark, specifically, a night scenein a city including artificial light and the like, normally, the camerais fixed using a tripod or the like, and long-exposure image pickupaccording to which the shutter mechanism of the camera in this state isreleased for a predetermined period of time (so-called bulb image pickupor time image pickup) is performed. When such long-exposure image pickupis performed, the image pickup device accumulates charges according tothe exposure time. An image according to the accumulated amount ofcharges may thereby be formed even for a dark scene, and thus, it iswell known that, for example, stars in the night sky, which are objectsof extremely low luminance, may be fixed as an image by performing along exposure.

However, in an image pickup environment where, although being a darkscene, a large amount of artificial light is included, such as a nightscene in a city, the artificial light may be reflected and diffused bydust in the air, clouds, or the like, resulting in the followingproblems. For example, the artificial light may negatively affect theentire image by causing color cast on the entire image including aregion which is supposed to be dark, such as a night sky, or causing theentire picked-up image to be bright against the intention of theoperator (user), or causing stars or the like emitting faint light to beerased by the artificial light and preventing the same from beingdisplayed, or preventing accurate color reproduction. For example, FIG.2 schematically shows the state which is actually seen by the human eye,and in this case, stars and the like are seen by the human eye in thesky region. However, if long-exposure image pickup is performed in thisstate, the sky region will be shown to be brighter than in reality bythe accumulation of harmful light components, as shown as the display onthe display section 18 in FIG. 3, and stars and the like will be erasedfrom the display image. The present invention performs an imagecorrection process of eliminating harmful light components such asartificial light that negatively affect a picked-up image, and acquiringan image that is closer to the way of being seen by human beings.

For this purpose, image pickup is performed by a long exposure for animage pickup target as shown in FIG. 2 by using the camera 1 of thepresent embodiment. Note that the camera 1 has a function that enables,even in a state where the shutter mechanism is released, checking of theaccumulation state of image data being acquired by the image pickupdevice 13, that is, checking, using the display section 18, at a timeinterval set in advance, of the state of an image being picked up,namely, a live bulb function or a live time function. This functionallows checking of progress of the exposure by the display on thedisplay section 18, and is thus helpful in deciding the timing of endingthe image pickup.

First, an operator (user) performs long-exposure image pickup of adesired image pickup target (see FIG. 2) using the camera 1. At thistime, image pickup is started using the live bulb function or the livetime function. Then, the state of the image being picked up is displayedon the display section 18 at a predetermined time interval. The operator(user) ends the exposure operation at a desired timing by looking at theimage pickup state displayed on the display section 18. An end operationof the exposure operation may be a touch operation on the touch panel 18b arranged on the display screen of the display section 18, or apressing operation of a shutter release button, for example.

In the example shown in FIG. 3, an end operation of the exposureoperation is performed by the operator (user) performing a touchoperation on an arbitrary position on the display screen showing theimage pickup state. At the same time, the touch position at this time ismade a specified position which is specified, by a hand or the like 100of the operator (user), as a position to be a “black” region.

Now, FIG. 5 is a conceptual diagram showing a change over time in theamounts of accumulated charges of RGB signals of a picked-up image. Achange over time in the amounts of accumulated charges at a specifiedpoint specified by a “black” region specification operation by theoperator (user) is shown by (a) in FIG. 5, and a change over time in theamounts of accumulated charges at a pixel region of the entire image isshown by (b) in FIG. 5.

As described above, when the operator (user) performs the “black” regionspecification operation as shown in FIG. 3, the signal processingcontrol section 11 of the camera 1 performs a subtraction process(correction process) for the accumulation results of the region of theentire image ((4-b) in FIG. 5) using the accumulation results of RGBsignals at the specified point ((4-a) in FIG. 5). Accordingly, signals(b′) from which the negative influence of the surrounding harmful lighthas been eliminated are kept. The image acquired by this calculationresult is displayed on the display section 18 of the camera 1, as shownin FIG. 4. Here, in the case of accepting the display result on thedisplay section 18, the operator (user) performs an operation using anoperation member such as an OK button (not shown), and then, the signalprocessing control section 11 of the camera 1 performs an operation ofstoring image data based on the image being displayed.

Note that, in the example described above, the exposure end operationand the “black” region specification operation are one touch operation,but such an example operation is not restrictive. For example, when anexposure is ended by a pressing operation on the shutter release buttonor the like, normally, an image based on the image data acquired by theimmediately preceding exposure operation is displayed immediatelythereafter on the display section 18 for a predetermined period of time(a preview image). The operator (user) may perform the “black” regionspecification operation during the display of the preview image. Notethat, although the word “black” is emphasized, not all the image datahas to be cancelled, and a method of suppressing the data accumulationto a specific level may also be applied.

Also, in the description above, the camera 1 is assumed to include thelive bulb function or the live time function, but these functions arenot necessarily required elements. The long-exposure image pickup may beperformed even if the camera 1 is not provided with the live bulbfunction or the live time function, and the appropriate exposure time inthis case may be easily set based on the experience or a plurality oftrials. The operator (user) may then perform the “black” regionspecification operation by a touch operation during display of a previewimage after an end operation for the exposure operation. Exactly thesame result as described above may be achieved by such an operation.Note that in the case of live bulb, the black at the time of touch maybe maintained. Although the word “black” has been emphasized, one doesnot have to think that all the image data has to be cancelled, and ausage is also possible according to which the color at the time of thetouch is taken as a specific level, and the data accumulation issuppressed to this level and no more accumulation is performed.

When the accumulated image signal of a specified region, which is aregion including a position (for example, a “black” region specifiedposition) on the image identified by the touch determination section 11c (position identification section), is subtracted from the accumulationresults of the entire image, there is a case where the value obtained bythe subtraction becomes negative.

Therefore, a limiter may be used in the subtraction process. Forexample, instead of subtracting the accumulated image signal of thespecified region, which is the region including the position (forexample, the “black” region specified position) on the image identifiedby the touch determination section 11 c (position identificationsection), from the accumulation results of the entire image, only aspecific ratio of the accumulated image signal of the specified region,for example, a half value of the accumulated image signal of thespecified region, may be subtracted from the accumulation results of theentire image. That is, the value to be subtracted in the subtractionprocess may be set to a predetermined value according to the accumulatedimage signal of the specified region (for example, the “black” region),which is the region including the position on the image identified bythe touch determination section 11 c (position identification section).

Next, the action of the camera 1 of the present embodiment describedabove will be described below using the flowchart of FIG. 6. FIG. 6 is aflowchart showing an example of the process sequence of the camera ofthe present embodiment (long-exposure image pickup).

First, it is assumed that the camera 1 of the present embodiment isactive and usable with the power being on. In this state, in step S101,the signal processing control section 11 checks whether or not theoperation mode that is currently set is an image pickup mode. In thecase it is confirmed here that the image pickup mode is set, the processproceeds to the next step S102. Also, in the case it is confirmed thatother than the image pickup mode is set, the process proceeds to stepS141.

In step S102, the signal processing control section 11 controls theaccessory communication section 32, and performs an accessorycommunication process. This accessory communication process is a processof checking whether or not the accessory 40 is attached to the camera 1,and in the case the accessory 40 is attached, a process of checking thetype and the like of the attached accessory 40 (a process of acquiringunique information, and the like), and a process of starting thecontrol, for example. The specific process is not directly relevant tothe present invention, and detailed description thereof is omitted.

Next, in step S103, the signal processing control section 11 controlsthe body-side communication section 12, and checks whether or not thelens barrel 20 is attached to the camera body 10, or checks whether ornot a lens change operation has been performed. In the case it isconfirmed that the lens barrel 20 is attached to the camera body 10, andthat the lens change operation is not performed, the process proceeds tothe next step S105. Also, in the case that the lens change operation hasbeen performed is confirmed, the process proceeds to step S104.

Note that, in the case it is confirmed in the process in step S103described above that the lens barrel 20 is not attached to the camerabody 10, the signal processing control section 11 controls the displaysection 18 to display an alarm to that effect or the like, to urge theoperator (user) to attach the lens barrel 20. Then, after confirming theattachment of the lens, a lens communication process in the next stepS104 is performed.

In step S104, the signal processing control section 11 performs the lenscommunication process with the lens control section 21 of the lensbarrel 20 through the body-side communication section 12 and thelens-side communication section 22. In this lens communication process,acquisition of information about the type or the like of the lens barrel20 that is attached is performed, for example. Then, the processproceeds to step S105.

In step S105, the signal processing control section 11 controls theimage pickup section including the image pickup device 13, the lens 26,and the like, the display section 18, and the like, and performs animage data acquisition process and a live view image display process. Atthe same time, the signal processing control section 11 performs aprocess of initializing the accumulation section 11 a. Then, the processproceeds to step S106.

In step S106, the signal processing control section 11 monitors a signalfrom the lens control section 21 through the communication sections 12and 22, and checks whether or not an operation instruction signal to begenerated by operation of the lens-side operation section 23 isgenerated, that is, whether or not an operation of the lens barrel 20,such as a zoom operation, a focus adjustment operation, or the like, isperformed. In the case some kind of lens operation is confirmed, theprocess proceeds to step S107. Also, in the case no lens operation isconfirmed, the process proceeds to step S108.

In step S107, the signal processing control section 11 performs apredetermined process of reflecting the result of the lens operationwhich has been confirmed, such as a zoom operation or a focus adjustmentoperation. Then, the process proceeds to step S108.

In step S108, the signal processing control section 11 monitors aninstruction signal from the operation section 15 on the side of thecamera body 10, and checks whether or not an operation of the camerabody 10, such as a menu operation or a mode switching operation, isperformed. In the case some kind of body operation is confirmed here,the process proceeds to step S109. Also, in the case no body operationis confirmed, the process proceeds to step S110.

In step S109, the signal processing control section 11 performs apredetermined process of reflecting the result of the body operationwhich has been confirmed, such as menu display and various relatedsetting change operations, a mode switching operation, or the like.Then, the process proceeds to step S110.

In step S110, the signal processing control section 11 monitors aninstruction signal from the operation section 15, the touch panel 18 b,or the like, and checks whether or not an instruction signal forstarting an image pickup operation has been issued. An instructionsignal for starting an image pickup operation is an instruction signalfrom the shutter release button included in the operation section 15, oran instruction signal from the touch panel 18 b, for example. In thecase an instruction for image pickup start is confirmed here, theprocess proceeds to step S111. Also, in the case an instruction forimage pickup start is not confirmed, the process returns to step S101described above.

In step S111, the signal processing control section 11 receives anoutput from the image pickup device 13, and starts a charge accumulationprocess by the accumulation section 11 a.

Next, in step S113, the signal processing control section 11 monitorsthe clock section 19, and checks whether or not a predetermined periodof time has passed from the start of image pickup. In the case passingof a predetermined period of time is confirmed here, the processproceeds to step S114. Also, in the case passing of a predeterminedperiod of time is not confirmed, the process proceeds to step S121.

In step S114, the signal processing control section 11 controls theaccumulation section 11 a, the image processing section 11 b, thedisplay control section 11 d, and the like, generates an image signalfor display based on image data which has been accumulated, and displaysa halfway image using the display section 18. Then, the process proceedsto step S121. By repeating this process, the image pickup state may bechecked on the display section 18 by the present camera 1 at a specifictime interval during the bulb image pickup or the time image pickup.

In step S121, the signal processing control section 11 monitors aninstruction signal from the touch panel 18 b, and checks whether or nota touch operation has been performed and, in the case a touch operationhas been performed, performs touch position identification by the touchdetermination section 11 c. Here, in the case no touch operation isconfirmed, the process returns to step S113 described above, and theprocess is repeated thereafter. Also, in the case a touch operation isconfirmed, touch position identification is performed, and then theprocess proceeds to the next step S122.

In step S122, the signal processing control section 11 controls theaccumulation section 11 a, the image processing section 11 b, thedisplay control section 11 d, and the like, and performs a correctioncalculation process of subtracting the result of charge accumulationcorresponding to the touch position confirmed and determined in theprocess in step S121 described above from the result of chargeaccumulation of the entire image, and also, performs a process ofcausing the display section 18 to display an image based on theprocessing result. Here, the image correction process mentioned above isperformed by the image processing section 11 b functioning as acorrection section. Furthermore, display of an “OK” icon or the like ina predetermined region of the display section 18 is performed. Icon dataor the like stored in advance in the storage section 14 or the temporarystorage section 16, for example, is used for the “OK” icon or the like.The operator (user) notifies the camera 1 of the acceptability of theimage that is currently displayed on the display section 18 (the imagereflecting the result of the subtraction process described above) byperforming a touch operation on the portion corresponding to the “OK”icon display. The acceptability of an image here is confirmationregarding whether or not the image is to be stored. Note that anoperation member such as an “OK” button (not shown) included in theoperation section 15 of the camera body 10 may be operated instead ofthe touch operation on the “OK” icon display.

In step S123, the signal processing control section 11 monitors aninstruction signal from the touch panel 18 b, the operation section 15,or the like, and performs a check regarding an instruction signalcorresponding to the “OK” icon display. Here, in the case an “OK”instruction is confirmed, the process proceeds to the next step S126.Also, in the case the “OK” instruction is not confirmed, the processproceeds to step S124.

In step S124, the signal processing control section 11 controls theaccumulation section 11 a, the image processing section 11 b, thedisplay control section 11 d, and the like, and performs a process ofdisplaying the result of accumulation prior to the subtraction processof the process in step S122 described above. Then, the process proceedsto step S125.

In step S125, the signal processing control section 11 checks whether ornot the charge accumulation operation by the accumulation section 11 ais to be continued, that is, whether or not the bulb image pickup or thetime image pickup is to be continued. Here, in the case of continuingthe charge accumulation operation (image pickup), the process returns tostep S111 described above, and the process is repeated thereafter. Also,in the case of not continuing the charge accumulation operation (imagepickup), the process returns to step S121 described above, and theprocess is repeated thereafter.

On the other hand, in the case an “OK” instruction is confirmed in theprocess in step S123 described above, and the process proceeds to stepS126, the signal processing control section 11 performs, in this stepS126, a compression storage process for the image that is currentlydisplayed on the display section 18, that is, image data correspondingto the image on which the subtraction process has been performed(temporarily stored in the temporary storage section 16). Then, theprocess returns to step S101.

On the other hand, in the case the operation mode set in the camera 1 isconfirmed in the process in step S101 described above to be other thanthe image pickup mode, and the process proceeds to step S141, the signalprocessing control section 11 checks, in this step S141, whether or notthe operation mode that is currently set is a reproduction mode. In thecase setting of the reproduction mode is confirmed here, transition to apredetermined reproduction process sequence takes place, and the processproceeds to step S142.

In step S142, the signal processing control section 11 controls thestorage section 14 and reads latest image data among pieces of imagedata stored in the storage medium, and after performing predeterminedsignal processing, controls the display section 18 and performs an imagereproduction process.

Next, in step S143, the signal processing control section 11 monitors aninstruction signal from the operation section 15 or the touch panel 18b, and checks whether or not an instruction for change of the displayimage has been issued. In the case it is confirmed here that aninstruction for change of the display image has been issued, the processproceeds to the next step S144. Also, in the case an instruction forchange of the display image is not confirmed, the process returns tostep S101 described above, and the process is repeated thereafter. Notethat the reproduction process sequence of the camera 1 of the presentembodiment is the same as that of a general, conventional camera.

On the other hand, in the case setting of other than the reproductionmode is confirmed by the process in step S141 described above,transition to the process sequence of another operation mode such as animage communication mode takes place. Note that other operation modesincluding the image communication mode are not directly relevant to thepresent invention, and detailed description thereof is omitted. Then,the process returns to step S101, and the process is repeatedthereafter.

Note that the signal processing control section 11 of the camera 1 ofthe present embodiment monitors instruction signals from the operationsection 15, the touch panel 18 b, or the like at all times. Then, in thecase an instruction signal from the operation section 15, the touchpanel 18 b, or the like is confirmed at any point during the processsequence described above, interruption for a process corresponding tothe instruction signal which has been confirmed is performed.Accordingly, regardless of the operation state of the camera 1, in thecase a predetermined interrupt signal (for example, a power off signal,a rest signal, or an operation switching signal) is confirmed, a processaccording to the interrupt instruction (for example, a power offprocess, a reset process, or an operation switching process) isperformed after the process currently under way is suspended, or afterthe process currently under way is completed.

Next, assuming an image pickup state (FIG. 2) different from the exampledescribed above, the action at the time of image pickup using the camera1 of the present embodiment will be described below. With respect to theimage pickup state described below, the example of the image pickupstate described above describes a state where a scene whose surroundingenvironment is relatively dark and artificial light or the like isincluded, such as a night scene in a city, is taken as the image pickuptarget. The example of the image pickup state described below assumes astate where, in the state similar to that of the example of the imagepickup state described above, a person or the like as a main object isfurther present at a distance relatively close to the camera 1 (forexample, about five meters or less from the position of the camera 1).

FIGS. 7 to 9 are conceptual diagrams for describing image pickup, inanother image pickup state, of a desired object by an operator (user)using the camera 1 of the present embodiment. Of these drawings, FIG. 7is a diagram showing a sketch of an image pickup range including a sightand a main object (person) as image pickup targets (predicted acquiredimage). FIG. 8 is a conceptual diagram showing picking up of the imagepickup targets in FIG. 7 using the camera 1 of the present embodiment.FIG. 9 is a conceptual diagram showing display, on the display section,of an image pick result (image) picked up using the camera 1.

In the image pickup state shown in FIG. 7, a person as the main objectis added to the image pickup target 200, which is in the state of FIG. 2described with reference to the example above, to obtain an image pickuptarget 201. With respect to image pickup in this state, control ofcausing a flash device (accessory 40) to emit light at a predeterminedtiming, such as immediately after the start of image pickup, or duringor immediately before the end of a long exposure (so-called slowsynchronization image pickup), is performed in addition to thelong-exposure image pickup. Accordingly, the main object (person) at aclose distance may be captured clearly and brightly by using the flashdevice, and at the same time, the background (dark scene) may becaptured brightly by the long-exposure image pickup. In this case, themain object (person) may move after the flashing of the flash device.According to the camera 1 of the present embodiment, a natural nightscene image may be acquired also in such an image pickup state byperforming an image correction process of removing the harmful lightcomponents in the sky region or the like.

That is, as in the example described above (FIG. 3), when the operator(user) performs the “black” region specification operation by a touchoperation by using the hand or the like 100, as shown in FIG. 8, thesignal processing control section 11 of the camera 1 performs asubtraction process for the accumulation results of the region of theentire image using the accumulation results of RGB signals at thespecified point, and may thereby eliminate the negative influence of thesurrounding harmful light. The image that is acquired as a result ofthis calculation is displayed on the display section 18 of the camera 1,as shown in FIG. 9. Note that, although the word “black” is emphasized,not all the image data has to be cancelled, and a method of suppressingthe data accumulation to a specific level may also be applied. This isbecause a small amount of harmful light may sometimes create a niceatmosphere. For example, an application method according to which thelevel of a touched portion is assumed to be “black” is also possible.

The action of the camera 1 in this case will be described below withreference to the flowchart in FIG. 10. FIG. 10 is a flowchart showinganother example of the process sequence of the camera of the presentembodiment (slow synchronization image pickup). Note that the flowchartin FIG. 10 is substantially the same as the flowchart in FIG. 6, withonly some of the processing steps being different. Accordingly, in thefollowing description, only the different processing steps will bedescribed in detail, and the same processing steps will be denoted bythe same step numbers, and description thereof will be omitted.

First, the camera 1 of the present embodiment is assumed to be activeand usable with the power being on. In this state, the signal processingcontrol section 11 checks, in step S101, whether or not the operationmode that is currently set is the image pickup mode. Each of theprocesses from step S101 to S110 below is exactly the same as that inthe flowchart in FIG. 6 described above.

When an image pickup operation is started in step S110, the signalprocessing control section 11 receives, in the next step S111A, anoutput from the image pickup device 13, and starts a charge accumulationprocess by the accumulation section 11 a. At the same time, the signalprocessing control section 11 controls the flash device as the accessory40 attached to the camera body 10, through the accessory communicationsection 32, and performs a flash operation according to the distance tothe main object. Control of the flash operation itself is normal flashcontrol performed by a general, conventional camera.

Next, in step S112, the signal processing control section 11 continuesthe charge accumulation process by the accumulation section 11 a. Thecharge accumulation process in this case is mainly performed for regionsother than a flash change point. The flash change point is a point(image region) where a clear change is made in an image region as aresult of flashing performed in step S111A described above. That is, byperforming the flashing described above, the main object (a person orthe like in the present example) present at a close distance is brightlycaptured. The region is taken as the flash change point. Determinationregarding the flash change point is performed in the following manner.That is, the amount of accumulated charges for a predetermined period oftime where flashing is performed and the amount of accumulated chargesfor a predetermined period of time where the flashing is not performedare compared, and if the former is greater, it is determined as theflash change point. Then, the process proceeds to step S113. Each of theprocesses in steps S113, S114 and S121 below is exactly the same as thatin the flowchart in FIG. 6 described above.

In the case a touch operation is confirmed and the touch position isdetermined in the process in step S121, and the process proceeds to thenext step S122A, the signal processing control section 11 controls, inthis step S122A, the accumulation section 11 a, the image processingsection 11 b, the display control section 11 d, and the like, andperforms a process of subtracting the result of charge accumulationcorresponding to the touch position confirmed and determined in theprocess in step S121 described above from the result of chargeaccumulation of the region of the entire image other than the flashchange point, and also, performs a process of causing the displaysection 18 to display an image based on the processing result.Furthermore, an “OK” icon or the like is displayed in a predeterminedregion on the display section 18. Then, the process proceeds to stepS123. Each of the processes from step S123 to S126 below is exactly thesame as that in the flowchart in FIG. 6 described above.

Note that each of the processes from step S141 to S145 performed in thecase the operation mode set in the camera 1 is confirmed to be otherthan the image pickup mode in the process in step S101 described aboveand the process proceeds to step S141 is exactly the same as that in theflowchart in FIG. 6 described above.

As described above, according to the embodiment described above, at thetime of image pickup by a long exposure, the image pickup device 13accumulates charges according to the exposure time. In this case, theaccumulation process is performed separately for each of the RGBsignals. Then, when the operator (user) specifies a position to be the“black” region by performing a touch operation on an arbitrary positionin the display screen while observing the image pickup state, the camera1 eliminates, in response, the negative influence from the harmful lightwith respect to the region including the “black” region specifiedposition mentioned above, and thus, image pickup for starlit sky or adark place may be easily performed by a simple configuration.

Note that in the embodiment described above, a process of subtractionfrom R, G, and B values is performed to sharpen the way the image in theblack region looks, but this means is not restrictive. For example, asanother embodiment, to make a point which is touched black, only theluminance value of the touch point is changed. In this case, the colorspace of the image region at the touch point, for example, R, G and Bsignals, is converted into Y (luminance signal), and Cb and Cr(color-difference signals), and the subtraction process with respect tothe result of charge accumulation is performed only for the Y (luminancesignal). Then, the color space conversion is performed again to regainR, G, and B. Also, although the word “black” is emphasized, not all theimage data has to be cancelled, and a method of suppressing the dataaccumulation to a specific level and taking the level as black may alsobe applied. In this case, subtraction with respect to the R, G, and Bvalues are performed to achieve the level.

As in the embodiment described above, for example, long-exposure imagepickup is performed with respect to a desired image pickup target (seeFIG. 2) by using the camera 1. The image pickup device 13 then startsaccumulation of the amount of charges. The operator (user) performs atouch operation on an arbitrary region on the display screen of thedisplay section 18 during the execution of the long-exposure imagepickup. The touch position at this time is the position specified by theoperator (user) as the “black” region. FIG. 11A shows, as in FIG. 5 ofthe embodiment described above, a conceptual diagram showing a changeover time in the amounts of accumulated charges of RGB signals of apicked-up image. Here, a change over time in the amounts of accumulatedcharges at a specified point specified by a “black” region specificationoperation by the operator (user) is shown by (a) in FIG. 11A, and achange over time in the amounts of accumulated charges at a region ofthe entire image is shown by (b) in FIG. 11A (same as in FIG. 5). FIG.11B is a diagram showing the concept of the amounts of accumulatedcharges after performance of color space conversion from the state inFIG. 11A.

In the embodiment described above, the signal processing control section11 of the camera 1 performs, using the accumulation results of RGBsignals at a specified point at the time of the “black” regionspecification operation ((4-a) in FIG. 5), the subtraction process(correction process) for the accumulation results of the region of theentire image at the same time point ((4-b) in FIG. 5). Thus, a processof acquiring an image from which harmful light has been removed byobtaining signals (b′) from which the negative influence of thesurrounding harmful light has been removed is performed.

On the other hand, in the present embodiment, the signal processingcontrol section 11 of the camera 1 performs conversion into Y, Cb, andCr signals from the R, G, and B signals of the accumulation results ofRGB signals at a specified point at the time of the “black” regionspecification operation ((4-a) in FIG. 11A) and the accumulation resultsof the region of the entire image at the same time point ((4-b) in FIG.11A) (see (5-b) in FIG. 11B). The difference value signals (shadedregions in 5(b) in FIG. 11B) between the accumulation results of the“black” region specified point and the accumulation results of theregion of the entire image are calculated based on these Y, Cb, and Crsignals (see 6 in FIG. 11B). The subtraction process performed at thistime is performed only for Y (luminance signal), for example. Then,color space conversion is performed again, and R, G, and B signals areregained (see 7 in FIG. 11B).

Also in this embodiment, the same result as in the embodiment describedabove may be obtained. Moreover, in the case of this means, since thesubtraction process is performed only with respect to the luminancesignal Y, color signals are not affected, and a correction process ofreducing the brightness without losing the color balance in the imagemay be performed.

Also, the following point may be taken into account with respect to thedegree of brightness correction process for a point specified by theoperator (user) by a touch operation. For example, a factor α accordingto the brightness at a touch point is determined. This factor α is setto be a greater value as the brightness is increased, as shown in FIG.12, for example. Here, FIG. 12 is a graph showing an example of arelation of the correction factor α to the brightness at a touchposition.

Then, a gamma table (tone correction table) or the like according towhich a dark portion is more suppressed as the correction factor α isgreater is prepared, and the brightness (luminance) correction processmay be performed using this table. For example, FIG. 13 is a graphshowing an example of a relationship between an amount of accumulatedcharges and an output (gamma table). Here, the solid straight line inFIG. 13 shows the amount of accumulated charges before correction. Whena correction process is performed on this straight line using thecorrection factor α, correction (table conversion) is performed suchthat the output is suppressed more for a region closer to a darkportion. In this case, the correction process may be performed for theRGB signals, or may be performed only for the Y signal after conversioninto Y, Cb, and Cr signals.

When such a correction process is performed, the color balance may bemaintained, and the brightness at a region which was nearly madeunnaturally bright due to the influence of harmful light or the like maybe suppressed, and a more natural image may be obtained, compared to acase of performing a luminance subtraction process or the like uniformlyon the entire image.

On the other hand, the following point may be taken into accountregarding the degree of range of a region on which the luminancecorrection process is to be performed, with respect to a point specifiedby the operator (user) by a touch operation.

For example, a touch specified point (a region where the luminancecorrection is desired to be performed; specifically, the region of thesky or the like) and another region (the region of stars, buildings, orthe like) are distinguished from each other, and the luminancecorrection process is desirably performed only for the former (theregion of the sky or the like).

To this end, a region with a small luminance difference, compared to aregion including the touch specified point, that is, a region where theluminance changes smoothly (gradation region) is determined to be theregion of the sky or the like, and a region with a great luminancedifference, that is, a region where the luminance changes drastically(for example, a part of artificial light such as neon lights, or abright part, in the gradation region such as the sky, such as a star) isdetermined to be another region. In this manner, determination may beperformed regarding whether a region in an image is a sky region oranother region, and the luminance correction process may be performedwith respect to the region of the sky or the like including the touchspecified point.

On the other hand, as another embodiment of the image correction processfor a result of charge accumulation, the following example isconceivable. As shown in FIG. 14 (conceptual diagram of an image pickuptarget, like FIG. 3), for example, with respect to a night scene in acity or the like, normally, in many cases, gradual gradation takes placealong a vertical line V running from the horizontal line along thevertical direction through a touch specified point T, that is, avertical line ab, in FIG. 14, in the screen connecting a point a and apoint b through the touch point T (a case where artificial light or thelike is not present on the straight line ab). Thus, brightnesscorrection may be performed according to a position, in the screen, inthe height direction, that is, a position on the vertical line ab.

Here, the vertical direction (height direction) of the screen may bedefined by defining the straight line ab in FIG. 14 by using a functionallowing detection of the attitude of the camera 1 based on the outputof a well-known electronic level, such as the acceleration/angularvelocity sensor 17, provided inside the camera 1. Also, the coordinatesof the touch specified point (reference sign T in FIG. 14) in the screenmay be determined by the touch panel 18 b.

Then, a correction factor regarding a gradational change at a positionalong the vertical direction of the screen (position on the straightline ab) is set, and the correction process for the touch specifiedpoint T is performed using the correction factor. In this case, thecorrection factor may be obtained in the following manner.

FIG. 15 is a conceptual diagram showing an example of a gradationalchange along the straight line ab (vertical line V including the touchpoint T) in FIG. 14. In FIG. 15, the vertical axis is the brightness,and the horizontal axis is the straight line ab. Here, a gradationalchange of gradual reduction in the brightness takes place along thestraight line ab, gradually from the point a to the point b.

In this case, the brightness at the touch point T on the straight lineab is indicated by the reference sign Tbr in FIG. 15, for example. Also,the brightness at an arbitrary point indicated by the reference sign Cxin FIG. 14 is obtained in the following manner. When a perpendicularline is drawn from a coordinate point of the reference sign Cx in FIG.14 toward the straight line ab, a point indicated by the reference signC in FIG. 14 is obtained. Here, with respect to the example of the imagepickup target shown in FIG. 14, the gradational change in the sky regionon the screen is assumed to correspond to a change along the straightline ab, and thus, the brightness at the arbitrary point Cx on thescreen may be assumed to be substantially the same as the brightness atthe point C on the straight line ab. Accordingly, the brightness at thepoint C on the straight line ab may be obtained as the reference signCbr shown in FIG. 15.

Then, the ratio (C/T) between the brightness at the touch point T andthe brightness at the point C is obtained. FIG. 16 is a graph showing anexample of a relationship between the ratio (C/T) between the brightnessat the touch point T and the brightness at the point C and the amount ofcorrection.

As shown in FIG. 16, in the case the brightness ratio between the touchpoint T and the point C (C/T) is 1, the positions of the touch point Tand the point C may be assumed to be substantially the same (C=T). Thetouch point T here is a region desired by the operator (user) to beblack, and thus, the amount of correction for the touch point T is setto the maximum. As for the correction process at this time, thecorrection process of the embodiment described above, or of otherexamples may be performed.

On the other hand, in the case the brightness at the point C is lessthan that at the touch point T ((C<T) or (C/T<1)), the position of thepoint C is assumed to be on the upper side in the screen than the touchpoint T (mainly, the region of the sky or the like). Accordingly, theactual brightness tends to be reduced as it gets closer to the upperside of the screen from the touch point T. Thus, in the region on theupper side of the screen than the position of C=T, correction isperformed such that the darkness is gradually increased from the touchpoint T toward the point b at the upper edge of the screen. That is, asshown in FIG. 16, setting is performed in such a way that the amount ofcorrection is gradually reduced from the touch point T toward the pointb.

On the other hand, in the case the brightness at the point C is greaterthan that at the touch point T ((C>T) or (C/T>1)), the position of thepoint C is more to the lower side of the screen than the touch point T.Accordingly, the actual brightness tends to be increased as it getscloser to the lower side of the screen from the touch point T. Thus, inthe region on the lower side of the screen than the position of C=T,setting is performed in such a way that the amount of correction is thesame for the region from the touch point T to the point b as for thetouch point T, as shown in FIG. 16.

According to this embodiment, the amount of correction is set accordingto the brightness at the touch specified point T, and thus, correctionis not overly performed, and an appropriate correction process may beperformed at all times. Note that, in each example described above, theimage correction process is expressed as the subtraction process or thelike, but the actual calculation processing is not restricted to thesubtraction process, and division, multiplication or the like may beperformed.

In the above-described embodiments, description has been made on theimage correction process performed for eliminating the negativeinfluence of the surrounding harmful light by subtracting theaccumulated image signal of the “black” region specified by the “black”region specification operation from the accumulated image signal at theregion of the entire image. However, the accumulated image signal of the“black” region is not necessarily subtracted from the accumulated imagesignal of the region of the entire image, but the accumulated imagesignal of the “black” region may be subtracted from an accumulated imagesignal of a part of an image region including at least the “black”region. In this case, the negative influence of the surrounding harmfullight can be eliminated.

Note that the present invention is not limited to the embodimentsdescribed above, and various modifications and applications may ofcourse be realized within the scope of the invention. Furthermore, theembodiments described above include inventions at various stages, andvarious inventions may be extracted by appropriately combining aplurality of disclosed structural elements. For example, in the casewhere, even if some of the structural elements are omitted from all thestructural elements indicated in the embodiment described above, theproblems to be solved by the invention may be solved, and the effects ofthe invention may be achieved, the configuration from which thestructural elements are omitted may be extracted as the invention. Thisinvention is not restricted by any specific aspects other than theappended claims.

The procedure of each processing sequence described in each embodimentdescribed above may be changed as long as the change does not contradictthe nature of the sequence. Accordingly, with the processing sequencesdescribed above, the execution order of each of the processing steps maybe changed, or a plurality of processing steps may be performedsimultaneously, or the order of each of the processing steps may bedifferent each time a series of processing sequence is performed.

That is, even if the operational flow is described in the scope ofclaims, specification, and drawings by using such terms as “first” and“next” for convenience, it does not mean that the operation needs to beperformed in the stated order. Also, it is needless to say the each stepconstituting the operational flows may be omitted as appropriate if thestep does not affect the essence of the invention.

Moreover, of the techniques described herein, the control and thefunctions described mainly with reference to the flowcharts may be, inmany cases, set by programs, and the control and the functions describedabove may be realized by a computer reading and executing the programs.The programs may be entirely or partially recorded or stored in aportable medium such as a non-volatile memory, such as a flexible diskor a CD-ROM, a hard disk, or a storage medium such as a volatile memory,as a computer program product, and may be distributed or provided at thetime of shipping or via a portable medium or a communication line. Auser may easily realize the image pickup apparatus of the presentembodiments by downloading the programs via a communication network andinstalling the programs in a computer, or by installing the programs ina computer from a storage medium.

The present invention is not restricted to the image pickup apparatus,which is an electronic apparatus specialized in the image pickupfunction such as a digital camera, but may be widely applied toelectronic apparatuses of other modes including the image pickupfunction, such as various types of electronic apparatuses with the imagepickup function including a mobile phone, an audio recording apparatus,an electronic diary, a personal computer, a game console, a TV, a clock,a navigation device using GPS (global positioning system), and the like.Furthermore, it is needless to say that application to an industrialapparatus or a medical apparatus which should allow accurate observationparticularly in a dark place is possible.

What is claimed is:
 1. An image pickup apparatus comprising: an image pickup section for picking up an image of an object and acquiring an image signal; an accumulation section for sequentially accumulating outputs from the image pickup section; a display section for visibly displaying an accumulated image signal of the accumulation section; a position identification section for identifying a position specified on an image displayed on the display section; and a correction section for performing an image correction process on the accumulated image signal of the accumulation section according to an identification result of the position identification section.
 2. The image pickup apparatus according to claim 1, wherein the image correction process by the correction section is a subtraction process of subtracting a predetermined signal from an accumulated image signal of at least a part of an image region, according to an accumulated image signal of a specified region which is a region including the position on the image identified by the position identification section.
 3. The image pickup apparatus according to claim 2, wherein the at least the part of the image region includes the specified region.
 4. The image pickup apparatus according to claim 2, wherein the image correction process by the correction section is calculation based on RGB signals of the accumulated image signal.
 5. The image pickup apparatus according to claim 2, wherein the image correction process by the correction section is calculation based on a luminance signal of the accumulated image signal.
 6. The image pickup apparatus according to claim 1, wherein the correction section performs the image correction process on the accumulated image signal of the accumulation section, based on an amount of correction set according to brightness at the position on the image identified by the position identification section.
 7. An image correction method comprising steps of: picking up an image of an object and acquiring an image signal by an image pickup section; sequentially accumulating outputs from the image pickup section by an accumulation section; visibly displaying an accumulated image signal of the accumulation section using a display section; identifying a position specified on an image displayed on the display section by a position identification section; and performing a correction process, by a correction section, on the accumulated image signal of the accumulation section according to an identification result of the position identification section.
 8. The image correction method according to claim 7, wherein the image correction process in the step of performing the correction process is a subtraction process of subtracting a predetermined signal from an accumulated image signal of at least a part of an image region, according to an accumulated image signal of a specified region which is a region including the position on the image identified by the position identification section.
 9. The image correction method according to claim 8, wherein the at least the part of the image region includes the specified region.
 10. The image correction method according to claim 8, wherein the image correction process in the step of performing the correction process is calculation based on RGB signals of the accumulated image signal.
 11. The image correction method according to claim 8, wherein the image correction process in the step of performing the correction process is calculation based on a luminance signal of the accumulated image signal.
 12. The image correction method according to claim 7, wherein, in the step of performing the correction process, the image correction process is performed on the accumulated image signal accumulated in the step of accumulating, based on an amount of correction set according to brightness at the position on the image identified in the step of identifying the position. 